The earliest Waterway Pass (Jinguan) site in China (202 BC- AD 420): a geoarchaeological approach

The Waterway Pass known as 'Jinguan' (津关) in China serves as a vital official facility to regulate waterway transportation systems and resources. The references to Jinguan found within historical documents, such as bamboo and wooden slips, have not yet yielded a thorough understanding of its exact location and architectural features. This study presents the first excavated archaeological site of Jinguan located in Southwest China—Chengba site—of which main remains are belong to the period about 2000 years ago. A comprehensive geoarchaeological investigation was conducted at the Chengba site, which included field geomorphological assessments and experimental analytical methods such as dating and sediment analysis (particle size, magnetic susceptibility, chroma, and soil micromorphology). The findings reveal that the sedimentary environment has changed from wet to dry, and the landforms have evolved from riverside beaches and lake marshes into floodplains and terraces. Furthermore, structures within Jinguan have adapted to changes in this region's micro-geomorphological environment. The findings of this research reconstruct the evolutionary process of ancient landforms associated with China's earliest Jinguan site; we also explore relationships between site selection, transformations in architectural styles, and hydrological shifts that occurred in Sichuan during the Han and Jin Dynasties.